The purpose of this classroom experiment was to examine the effects of Inter‐ethnolinguistic Peer Tutoring (IEPT) on the social interaction and English language proficiency of Spanish‐speaking elementary children. The relationship between verbal interaction in English and growth in English language proficiency was also examined. A matched pairs experimental design was employed. Subjects were tested on three measures of English language proficiency, the PPVT, the LAS and the CCCT. They were observed to determine the degree to which they interacted in English with fluent English speakers. They were then matched on the basis of an overall English proficiency score and an interaction score, and were assigned to a treatment or control group. The IEPT treatment consisted of sessions designed to provide a structured setting for natural language practice between an LES and an FES student. Students were observed weekly for verbal interactions during their free time. They were posttested on the three measures of English language proficiency. A trend analysis, correlations, andttests provided some evidence that the IEPT treatment resulted in increased verbal interaction in English. No relationship was demonstrated between amount of verbal interaction in English and growth in English language proficiency based on an analysis using partial correlations. The results ofttests revealed that the IEPT treatment resulted in increased vocabulary comprehension as measured by the PPVT, but no differences between treatment and control group were found on the LAS and the CCCT tests. The discussion emphasizes the importance of utilizing the language input of FES children in designing ESL progr